The proclamation that sanctioned the birth of the unified Kingdom of Italy came into force on 17 March 1861. Victor Emmanuel, first King of Italy, presiding.
The Meiji Restoration brought practical imperial rule to Japan in 1868 creating, arguably for the first time, a central government which exercised direct power through the entire realm. Emperor Meiji presiding.
The Unification of Germany into the German Empire, a Prussia-dominated nation state with federal features, officially occurred on 18 January 1871. Kaiser Wilhelm I presiding.
There is a strong case then for asserting that the Axis powers, the military coalition that fought in World War II against the Allies, comprised three modern countries founded within a decade of each other.
Let's date their alliance to the Tripartite Pact, an agreement between Germany, Italy and Japan signed in Berlin on 27 September 1940.
It is longer from the birth of the Kingdom of Italy to the Tripartite Pact, than it is from the Tripartite Pact to today.